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Diffstat (limited to 'third_party/rust/rayon/src/iter/flatten.rs')
-rw-r--r-- | third_party/rust/rayon/src/iter/flatten.rs | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/third_party/rust/rayon/src/iter/flatten.rs b/third_party/rust/rayon/src/iter/flatten.rs new file mode 100644 index 0000000000..29d88f99ed --- /dev/null +++ b/third_party/rust/rayon/src/iter/flatten.rs @@ -0,0 +1,140 @@ +use super::plumbing::*; +use super::*; + +/// `Flatten` turns each element to a parallel iterator, then flattens these iterators +/// together. This struct is created by the [`flatten()`] method on [`ParallelIterator`]. +/// +/// [`flatten()`]: trait.ParallelIterator.html#method.flatten +/// [`ParallelIterator`]: trait.ParallelIterator.html +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Debug, Clone)] +pub struct Flatten<I: ParallelIterator> { + base: I, +} + +impl<I> Flatten<I> +where + I: ParallelIterator, + I::Item: IntoParallelIterator, +{ + /// Creates a new `Flatten` iterator. + pub(super) fn new(base: I) -> Self { + Flatten { base } + } +} + +impl<I> ParallelIterator for Flatten<I> +where + I: ParallelIterator, + I::Item: IntoParallelIterator, +{ + type Item = <I::Item as IntoParallelIterator>::Item; + + fn drive_unindexed<C>(self, consumer: C) -> C::Result + where + C: UnindexedConsumer<Self::Item>, + { + let consumer = FlattenConsumer::new(consumer); + self.base.drive_unindexed(consumer) + } +} + +/// //////////////////////////////////////////////////////////////////////// +/// Consumer implementation + +struct FlattenConsumer<C> { + base: C, +} + +impl<C> FlattenConsumer<C> { + fn new(base: C) -> Self { + FlattenConsumer { base } + } +} + +impl<T, C> Consumer<T> for FlattenConsumer<C> +where + C: UnindexedConsumer<T::Item>, + T: IntoParallelIterator, +{ + type Folder = FlattenFolder<C, C::Result>; + type Reducer = C::Reducer; + type Result = C::Result; + + fn split_at(self, index: usize) -> (Self, Self, C::Reducer) { + let (left, right, reducer) = self.base.split_at(index); + ( + FlattenConsumer::new(left), + FlattenConsumer::new(right), + reducer, + ) + } + + fn into_folder(self) -> Self::Folder { + FlattenFolder { + base: self.base, + previous: None, + } + } + + fn full(&self) -> bool { + self.base.full() + } +} + +impl<T, C> UnindexedConsumer<T> for FlattenConsumer<C> +where + C: UnindexedConsumer<T::Item>, + T: IntoParallelIterator, +{ + fn split_off_left(&self) -> Self { + FlattenConsumer::new(self.base.split_off_left()) + } + + fn to_reducer(&self) -> Self::Reducer { + self.base.to_reducer() + } +} + +struct FlattenFolder<C, R> { + base: C, + previous: Option<R>, +} + +impl<T, C> Folder<T> for FlattenFolder<C, C::Result> +where + C: UnindexedConsumer<T::Item>, + T: IntoParallelIterator, +{ + type Result = C::Result; + + fn consume(self, item: T) -> Self { + let par_iter = item.into_par_iter(); + let consumer = self.base.split_off_left(); + let result = par_iter.drive_unindexed(consumer); + + let previous = match self.previous { + None => Some(result), + Some(previous) => { + let reducer = self.base.to_reducer(); + Some(reducer.reduce(previous, result)) + } + }; + + FlattenFolder { + base: self.base, + previous, + } + } + + fn complete(self) -> Self::Result { + match self.previous { + Some(previous) => previous, + None => self.base.into_folder().complete(), + } + } + + fn full(&self) -> bool { + self.base.full() + } +} |